Metal‐Reduction‐Induced Dechlorination Coupling for Constructing All‐Inorganic Crosslinked Cyclotriphosphazene Networks With In Situ Metal Embedding

ABSTRACT The metal‐reduction‐induced dechlorination coupling (MR–DC) strategy enables the first successful synthesis of an all‐inorganic crosslinked phosphazene network (aPN) from hexachlorocyclotriphosphazene (HCCP) under mild reaction conditions. Using Cu as a model, the resulting Cu–aPN (copper‐embedded all‐inorganic phosphazene network) retains the intrinsic N 3 P 3 backbone and exhibits an amorphous structure where Cu species are uniformly anchored at dense P/N coordination sites of the network. Time of flight secondary ion mass spectrometry (TOF‐SIMS) and X‐ray diffraction (XRD) reveal a gradual CuCl‐to‐CuO phase conversion during ammonia treatment, which effectively ensures the structural stability of the phosphazene framework. In 1 M KOH, Cu–aPN delivers an overpotential of 280 mV at 10 mA cm −2 and a Tafel slope of 48 mV dec −1 , markedly outperforming Ga–aPN. In situ Raman and density functional theory (DFT) analyses indicate stronger Cu–P/N coordination coupling that lowers the *OH formation barrier (0.39 vs. 0.88 eV for Ga). This MR–DC route furnishes a general and versatile pathway for constructing metal‐embedded all‐inorganic phosphazene frameworks with tunable coordination environments for advanced electrocatalytic applications.